Apparatus for making plastic containers

ABSTRACT

Methods of and apparatus for making plastic containers with integral rims, utilizing a transfer ring means having an aperture and an annular groove, in which the aperture is closed to define a space for reception of thermoplastic material, which is compressed to form it into a diaphragm with the material filling said groove forming the rim of the diaphragm, the transfer means carrying the diaphragm is positioned on a mold having a cavity corresponding to the shape of the container, the diaphragm is formed into a container in the mold cavity, and the container is removed from the transfer means with the rim of the diaphragm as molded in said groove intact with the container and forming the rim of the container.

This is a division of application Ser. No. 456,074, filed Mar. 29, 1974,now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to apparatus for making plastic containers, andmore particularly to apparatus for making plastic containers withintegral rims.

The invention is an improvement upon the invention of U.S. Pat. No.3,602,946, which generally involves the formation of a diaphragm ofplastic material in a transfer ring with the periphery of the diaphragmretained in an internal annular groove of the ring, and the transfer ofthe ring carrying the diaphragm to a molding station where the diaphragmis molded into a container, followed by the severance of the containerfrom the annulus of the plastic material retained in the groove. Thisannulus is either discharged as waste, or it is suggested that the nextdiaphragm to be formed may be welded thereto so as to minimize waste.The latter, however, has not been practical in commercial production.

SUMMARY OF THE INVENTION

Among the several objects of this invention may be noted the provisionof improved apparatus for making plastic containers involving theformation of a diaphragm in a transfer means (e.g., a transfer ring) andthe transfer of the transfer means to a molding station where thediaphragm is molded into a container, without any waste of the plasticmaterial, and without any severing operation such as above described;and the provision of such improved apparatus for producing containerswith integral rims without any waste of plastic material.

In general, apparatus of this invention comprises means for firstmolding a pre-form and means for then molding the pre-form into acontainer having an open end. The pre-form molding means comprises atransfer means having opposite sides, an aperture therethrough from oneside to the other, and a groove formation surrounding the apertureadapted to receive plastic during the molding of the pre-form anddefining the configuration for the open end of the container, wherebythe open end of the container is molded as an integral part of thepre-form when the pre-form is molded. The apparatus has a station forthe molding of the pre-form with means at this station for closing theaperture in the transfer means comprising a metering plate on one sideand a compression means on the other side of the transfer means. Thecompression means comprises a compression ring and a compression pistonmovable in the compression ring, the latter having an end engageablewith the said other side of the transfer means around said aperture atthe location of the groove formation in the transfer means, and beingmovable relative to the metering plate from an open position relative tothe transfer means and the metering plate and a closed position whereinsaid end of the compression ring engages said other side of the transfermeans and clamps the transfer means between the metering plate and thecompression ring thereby to form a closed space including the aperturein the transfer means and the said groove formation for the molding ofthe pre-form. The metering plate has a passage for flow of plastic intosaid closed space, and means is provided for delivering into said closedspace through said passage a volume of thermoplastic plastic less thanthe volume of said closed space. The compression piston is then movablein and relative to the compression ring in the direction toward themetering plate to compress the plastic in said closed space and form itinto the pre-form, with the plastic filling said groove formationthereby to mold the open end of the container which is to be formed fromsaid pre-form as an integral part of the pre-form and also to retain thepre-form in the transfer means.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in cross section showing certain parts of an apparatusof this invention in a clamped position;

FIGS. 2-13 show the same and other parts and diagrammatically illustratesuccessive steps in the operation of a preferred embodiment of thisinvention;

FIG. 14 illustrates a modification having a single transfer body;

FIG. 15 illustrates another modification having a single transfer body;

FIG. 15a is a view similar to FIG. 15 showing a modification of FIG. 15;

FIG. 16 is a view showing a step in the method utilizing the singletransfer body of FIG. 14;

FIG. 17 is a view showing a step in the method utilizing the singletransfer body of FIG. 15;

FIGS. 18-24 are sectional views showing parts of alternative embodimentsof the internal edges of transfer bodies;

FIGS. 25 and 26 illustrate the formation of non-planar plastics materialdiaphragms or pre-forms;

FIG. 27 illustrates the formation of a plastics material diaphragm orpre-form of non-uniform thickness; and

FIG. 28 is a view showing a modification wherein a circumferentialmovement is imparted to plastic material as it is introduced andcompressed to form a diaphragm or pre-form in a transfer body.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is an improvement in, or modification of, theinvention described and illustrated in U.S. Pat. No. 3,602,946, issuedSept. 7, 1971 (see also British patent specification No. 1,230,282).Accordingly, the description and drawings in the present application areconfined principally to the improved or modified features of theprocesses and apparatus. Reference is directed to the specification ofU.S. Pat. No. 3,602,946 for a disclosure of any features which are notfully described or illustrated herein.

The different successive operations in a heat-shaping process inaccordance with the invention will now be described with reference toFIGS. 1-13. FIG. 1 illustrates an injection and compression device in aclamped position and shows upper and lower transfer rings 1, a one-piecetransfer plate 2 (corresponding to transfer plate 2 shown in U.S. Pat.No. 3,602,946) formed with a recess having an internal lip which cansupport the rings 1, a compression ring 3a, a compression piston 3b, aninjection or metering plate 4 and a conduit 20 affording an injectionnozzle through which plastics material in a moldable state is suppliedto the cavity defined between the compression piston 3b and theinjection plate 4.

FIG. 2 shows the transfer rings 1 having an aperture therethrough. Therings are located in the recess of the transfer plate 2 and aresupported from beneath by the aforementioned lip of that plate. Therings 1 occupy a position ready for injection and are placed between thecompression piston 3b and the injection or metering plate 4. Theinjection nozzle conduit 20 is closed in the position shown in FIG. 2 ofthe drawings. The compression ring 3a and the compression piston 3b aredisplaced towards the injection plate 4 so that the rings 1 are clampedagainst the injection plate 4 thus sealing the upper part of theaperture. The rings 1 simultaneously reach a position in which they aresubstantially coplanar with the top of the ring 3a which ring closes thelower part of the aperture as shown in FIG. 3. The rings 1 and thepiston 3b thus form a recess or cavity 5 into which plastics material 6is introduced through an aperture in the injection plate 4 as shown inFIG. 4.

As the distance between the end face of the piston 3b and the injectionplate 4 is small, the plastics material 6 spreads in the recess orcavity 5 which recess or cavity is shaped to mold a thick pad whosediameter, as shown in FIG. 4, will be less than that of the recess orcavity 5 itself. During injection of the plastics material 6 into therecess or cavity 5, a circumferential movement may be imparted to themelt by rotating the compression piston 3b within the ring 3a. Thepurpose of the circumferential movement is to impart a circumferentialas well as a radial orientation whilst the plastic is being injected inorder to achieve biaxial orientation in the plastic diaphragm orpre-form which is subsequently formed. The plastics material 6 is thusbrought into the form of a thick pad without having been put underhigher pressure. This is important as it makes it unnecessary to use ahigh injection pressure. Simple and conventional injection means maythus be employed to introduce the plastics material into the recess orcavity 5.

Once the desired amount of plastics material has been introduced intothe recess or cavity 5, the conduit 20 affording the injection nozzle isclosed and the piston 3b is displaced towards the injection plate 4 soas to close the upper part of the axial aperture in the rings 1 as shownin FIG. 5. The plastics material 6 is highly compressed during thisdisplacement and is formed into a diaphragm or pre-form 6a whoseperiphery is engaged in a retaining groove 7 formed between radiallyinner regions of the two rings 1 in order to secure the diaphragm 6a tothese rings. A further circumferential movement may be imparted to thematerial 6 (melt) by rotating the compression piston 3b within the ring3a during the compression of the pad of material 6 to form the diaphragm6a. The purpose of thie circumferential movement is to impart acircumferential as well as a radial orientation whilst the plastic isbeing compressed in order to achieve biaxial orientation in the plasticdiaphragm 6a.

It should be noted that substantially no force is applied to thetransfer plate 2 as the rings 1 are removably located thereon and that,during injection (FIG. 4) and compression (FIG. 5), the rings 1 are heldclamped between the compression ring 3a and the injection plate 4. Onlythe temperature of the piston 3b and the plate 4 has to be controlled tomaintain the diaphragm 6a of plastics material at its shapingtemperature.

The compression ring 3a and compression piston 3b are then re-lowered asshown in FIG. 6 of the drawings so that the rings 1 resume their normalposition in the transfer plate 2 carrying the diaphragm 6a whoseperiphery is secured in the groove 7 between the rings 1. The diaphragm6a of compressed plastics material is thus in contact substantially onlywith the surrounding air which will conduct heat away from the diaphragmonly relatively slowly.

The lower ring of the two-part transfer ring 1, 1 has a downwardlyflaring seat 71 around the aperture therein, and the upper ring of thetwo-part transfer ring 1, 1 has an upwardly flaring seat 72 around theaperture therein (see FIG. 2). The compression ring 3a has a flaringupper end 73 engageable with the seat 71 of the lower ring, and theinjection plate 4 has a lower portion 74 formed to fit in the aperturein the upper ring and having a flaring periphery 75 engageable by theseat 72 of the upper ring. When the rings 1, 1 are clamped (as shown inFIG. 3) the upper edge of the flare 73 is located generally at the upperedge of the flare 72, and the bottom face of portion 74 of the injectionplate is generally in the horizontal plane of the lower edge of theflare 72 (at the top of groove 7). Flare 73 seats and seals against seat71, and seat 72 seats and seals against flare 75.

FIGS. 7 and 8 of the drawings show a forming station in which therequired container is first shaped mechanically after which it isbrought to its final form by inflation and/or vacuum shaping as shown inFIG. 9. The shaping device can be of any suitable configurationdepending upon the desired shape of the containers. As shown, a die ormold 10 and a punch 9 are arranged at opposite sides of the transferplate 2 and are located so as to be aligned with the apertures in thatplate when it is in one of its rest positions (which are shown in FIG.25 of U.S. Pat. No. 3,602,946). The punch 9 is displaced through therings 1 located in the aperture of the plate 2 to draw the diaphragm 6ainto the interior of the cavity in the die or mold 10. The diaphragm 6ais then inflated so as to press it against the walls of the mold andform the container (see FIG. 9).

The punch 9 and the die 10 are next moved apart as shown in FIG. 10 ofthe drawings to allow the transfer plate 2 to move to another operatingstation taking with it the transfer rings 1 with a formed container 8attached thereto as shown in FIG. 11. This station is provided withlower and upper abutment assemblies 11 and 12 and relative upward anddownward movements of the vertical rods of these move the two rings 1,which are formed with at least two holes each for cooperation with thealigned rods, apart and release the formed container 8 to stand upon thelower abutment assembly 11 as shown in FIG. 12 of the drawings. Thecontainer 8 is then ejected by mechanical, pneumatic or other suitablemeans that are not illustrated. It is emphasized that the describedconstruction insures that the container lips are released and ejectedwith the corresponding containers 8.

It will be noted from the foregoing that the main points of the processthat has been particularly described are:

a. Injection at reduced pressure of a pad of plastics material into arecess or cavity which is shaped to produce two equi-spaced faces onsaid pad but which does not limit the radial expansion of the pad duringintroduction of plastics material into the recess or cavity.

b. Compression of the pad of plastics material to mold it into apre-form in the shape of a diaphragm and simultaneously to cause thediaphragm to be held, at its periphery only, by the transfer rings.

c. Transfer of the diaphragm (the pre-form) to the shaping station.

d. Transfer of the formed container to the ejection station.

e. Elimination or reduction in the volume of plastics material waste.

Waste is substantially completely eliminated where the whole diameter ofeach plastics material diaphragm is used in the finished container. Insuch a case, the internal edges of the transfer rings 1 define the finallip shape, i.e. the shape of the open end of the containers 8.

The advantages of the process that has hereinbefore been particularlydescribed as compared with many previously proposed processes aremainly:

a. The substantial elimination or marked reduction in waste whichresults in lowering the cost price for the manufacture of eachcontainer.

b. Reduction in the thickness of the walls of the containers owing tothe uniformity of the diaphragm of plastics material from which thecontainers are produced. It follows that the weight of plastics materialused for the production of a given container 8 having requiredmechanical characteristics is reduced, thus entailing a similarreduction in the cost price of each container.

c. The symmetry between the diaphragm 6a and the finished container 8enables radial thickness variations to be compression molded into thediaphragm to compensate for the thinning of the angular corners of thefinished container which normally occurs when thermoforming from aparallel sided plastics sheet.

d. The preparation of the diaphragms 6a for forming with radiallysymmetric orientation, thus providing conditions for improved physicalproperties of the finished containers 8.

e. Accurate dimensioning of the container lips by compression forminginto the groove 7 between the transfer rings 1, this feature being mostimportant to insure easy and correct lid fitting.

f. A number of different lip forms (container open end) can be producedby employing appropriately shaped transfer rings 1, this normallyrequiring the use of separate forming processes in more conventionalthermoforming methods or being substantially impossible on someconventional thermoforming lines.

g. Omission of heating and temperature regulation for the transferdevice.

h. Simplification of the injection mechanism, injection being effectedat a very low pressure which need not be much greater than atmosphericpressure.

i. Construction of a transfer device which is not subjected to forcesdue to compression, injection or shaping of the plastics material. Thisis due to the construction and arrangement of the transfer rings whichare mounted freely on the transfer plate 2 to which they do not transmitany significant forces.

j. Finally, the process can be used for substantially any type ofheat-shaping such as mechanical, pneumatic, pressure-shaping,vacuum-shaping with or without counter-blowing and so on as the shapingstation is independent of the remainder of the apparatus. Consequently,the most suitable shaping process can be selected depending on theconfiguration of the container that is to be made and upon theparticular plastics material that is to be used. A method of shapingwhich is particularly well adapted to the present process is describedin British patent specification No. 972,488.

One preferred heat-shaping apparatus for use in the present inventioncomprises a transfer device in which the transfer plate 2 is a rotaryplate (as in U.S. Pat. No. 3,602,946) provided with apertures which aredistributed uniformly on a circumference close to the periphery of theplate, said apertures being arranged to receive the transfer bodies thatare afforded by the rings 1. The rings 1 can be indexed intosimultaneous alignment with three stations which comprise the injectionand compression station illustrated in FIG. 1, the shaping stationillustrated in FIG. 7 and the ejection station that is illustrated inFIG. 11.

The process that has been described above can take place by rotating thetransfer plate 2 in a step-by-step manner so as to convey the transferrings 1, in turn, to each of the three stations that have just beenmentioned. It will be apparent that, when the injection and compressiondevice that has been described with reference to FIG. 1 of the drawingsis employed, the plate 2 is brought to a corresponding angular positionin which one of the apertures therein has its center in line with thecompression ring 3a and the compression piston 3b. The free face of theinjection plate 4 is flat apart from the provision of an injectionpassage or orifice constituted by a hole 76 at its center, said orificeor hole 76 having a diameter of not less than 2 millimeters and beingsupplied with plastics material in a moldable state by the conduit 20that affords the injection nozzle. Shut-off of the nozzle outlet of theconduit 20 after the injection of plastics material is achieved bymoving said conduit laterally to bring it out of register with theinjection orifice in the plate 4. This movement has a slicing actionthrough the plastics material and, in the closed position of the conduit20, a flat end face of the conduit 20 that surrounds the injectionaperture therein is brought into closing register with the injectionorifice or hole 76 in the plate 4. This condition is illustrated in FIG.5 of the drawings. FIGS. 25 and 26 of the drawings illustratealternative constructions in which the compression-formed plasticspre-form is of non-planar configuration but in which the thickness ofthe pre-form remains substantially uniform throughout its area. FIG. 27of the drawings illustrates a construction in which the pre-form is ofnon-uniform thickness and non-planar formation, its lip also being ofreduced thickness as compared with the remainder thereof. Thearrangements shown in FIGS. 25-27 of the drawings are only examples ofmany different pre-form shapes that are possible. As illustrated, thehole 76 is formed of frusto-conical shape. Plastic compressed in thehole constitutes part of the pre-form and is separable with the pre-formfrom the metering plate 4.

The compression piston 3b may have its temperature controlled by thecirculation therethrough of a heating or cooling fluid in at least oneradial zone thereof to bring the diaphragm 6a to the correctcontainer-forming temperature throughout its area. For a given plasticsmaterial and a desired diaphragm thickness (volume of plasticsmaterial), the temperature of the parts 3b and 4, the distance betweenthem when the plastics material is injected, the speed of injection, andthe residence time for cooling, are critical parameters which can bedetermined experimentally depending on the particular operatingcircumstances. Optimization of these parameters is effected on the basisof the result obtained when shaping a diaphragm, i.e. upon the qualityof the container that is produced.

The transfer of one of the diaphragms 6a into the shaping device can beeffected in one or more successive steps corresponding to successiveangular displacements of the plate 2 according to the relative positionof the injection and compression devices and the shaping device. Thetime taken to transfer the diaphragm 6a may be controlled to vary theextent of cooling of the diaphragm by contact with air between thecompression and forming stations. This time will depend on thedifference in temperature necessary for forming the plastics materialand upon the temperature thereof at the instant of release from thecompression station. It is obvious that a number ofinjection-compression, shaping and ejection cycles can be carried outsimultaneously. In fact, for each angular rest position of the transferplate 2, the injection-compression, shaping and ejection operations canbe carried out simultaneously by different transfer rings 1.

To increase the speed of container production, the apparatus can includea plurality of injection-compression, shaping and ejection devices whichcooperate with a single transfer plate 2. Likewise, displacement of thetransfer plate 2 could be linear rather than circular if the deviceswhich cooperate with the transfer rings 1 that are carried by said plateare located correctly with respect to the rest positions of the transferplate 2. Additionally, the transfer rings 1 have been described as beingcircular but their shapes when seen in plan can be other than circular.The transfer rings 1 could, for example, be oval or oblong when it isdesired to produce a container of a particular shape or when a number ofcontainers are to be shaped simultaneously from a single diaphragm ofplastics material by means of a shaping tool having a plurality ofpunches and dies. In such cases, the shapes of the parts 3a, 3b and 4,the shaping tool and the shearing means would have to match the transferrings 1.

FIGS. 14, 15, 15a, 16 and 17 of the drawings illustrate alternativeembodiments of the injection and compresson device in which the transferrings 1 are single units instead of being afforded by separated upperand lower rings 1 as described above. In the construction shown in FIGS.14 and 16 of the drawings, a single upper carrier ring 1a is employedand the plastics diaphragm is retained in that ring during transfer bythe use of a reverse taper 42. When the diaphragm reaches the formingstation shown in FIG. 16, the container is formed below the singlecarrier plate and the upper lip of a forming cavity 43 is used to clampthe diaphragm during the forming operation.

In the constructions shown in FIGS. 15, 15a and 17, a single lowercarrier ring 1b is used and the diaphragm of plastics material isretained in that ring, during transfer, by engagement with a raised edgeor lip 44 thereof. FIGS. 15 and 15a show two slightly differentconfigurations of the raised edge 44 which will result in correspondingconfigurations of the lip of the diaphragm but, in either case, when thediaphragm reaches the forming station shown in FIG. 16, the container isformed above the single carrier plate and the lower lip of the formingcarrier 43 clamps the diaphragm in position during the formingoperation.

FIGS. 18-24 of the drawings all show, in cross section, examples ofvarious container lip configurations that can be produced by employingappropriately shaped transfer rings 1. It will be evident from FIGS.18-24 of the drawings that all of the diaphragm lips will be effectivelyretained in the cavities afforded between the radially inner edges ofthe upper and lower rings 1 until those rings are parted in the mannershown in FIG. 12 of the drawings, immediately prior to ejection of aformed container.

From the above, it will appear that the invention basically involves theutilization of a transfer means having an aperture and a grooveformation 7 surrounding the aperture, this transfer means beingconstituted, for example, by the two rings 1 of FIGS. 1-13 or the singlering 1a of FIGS. 14 and 16 or the single ring 1b of FIGS. 15, 15a and 17and

a. The closing of the aperture to define a space (e.g., the space 5) forreception of the thermoplastic material 6;

b. The introduction into said space of a volume of the thermoplasticmaterial less than the volume of said space (as shown, for example, inFIG. 4);

c. The compression of the material (as by piston 3b) in said space toform it into a pre-form such as a diaphragm (6a) with the materialfilling the groove formation (e.g., the groove 7 of rings 1) and formingthe rim of the pre-form and retaining the diaphragm in the transfermeans;

d. Positioning the transfer means carrying the pre-form on a mold (e.g.,the mold 10 shown in FIGS. 7-10) having a cavity corresponding to theshape of the container;

e. Forming the pre-form into a container in the mold cavity, as shown,for example in FIGS. 8 and 9; and

f. Removing the container from the transfer means, as shown, forexample, in FIG. 12, with the rim of the pre-form (indicated at R inFIG. 12) as molded in the said groove intact with the container andforming the rim (the open end) of the container.

Step (a) is carried out as shown in FIG. 1, for example, via theinjection or metering plate 4 on the upper side and the compressionpiston 3b on the lower side of the transfer means, and step (c) by theupward movement of the compression piston 3b. In the case where thetransfer means comprises the two axially separable rings 1, thecontainer is removed by axially separating the two rings 1 and movingone of them (the upper ring) axially upwardly relative to the containeraway from the top of the rim R of the container to a position above therim R of the container and the other (the lower ring) axially downwardlyto the container away from the bottom of the rim to a position such asshown in FIG. 12 wherein the rings are spaced a distance greater thanthe height of the container, the upper ring is above the container andthe lower ring is sufficiently clear of the bottom of the container toenable the container to be removed laterally between the rings. Thispositions the rings 1 clear of the ends of the container so that it maybe ejected laterally. In the case where the transfer means comprises thesingle transfer ring 1a with the reverse tapered or undercut groove inthe bottom side of the transfer ring, the aperture in the transfer ringis closed on the top by the injection plate 4 and on the bottom by thecompression ring 3a and compression piston 3b in the compression ring,the rim of the diaphragm (and rim of the container) is formed in thegroove 7 between the transfer ring and the compression ring as shown inFIG. 14, and the transfer ring is applied to the upper end of the moldas appears in FIG. 16 with the rim of the diaphragm clamped between thetransfer ring 1a and the upper end of the mold 9. The rim of thecompleted container may be removed from the undercut groove by pushingit downwardly out of the groove. In the case where the transfer meanscomprises the single transfer ring 1b with the groove in the upper sideof the transfer ring, the aperture in the ring is closed as before bythe injection plate 4 on top and the compression ring 3a and compressionpiston 3b on the bottom, the rim of the diaphragm is formed in thegroove 7 between the transfer ring and the injection plate as shown inFIG. 15, or FIG. 15a, and the transfer ring is applied to the lower endof the mold as appears in FIG. 17 and the rim of the diaphragm isclamped between the transfer ring and the lower end of the mold.

Reference has been made above to imparting a circumferential movement tothe melt (plastic material) during its injection into the recess orcavity 5 and again while it is being compressed for biaxial orientation.FIG. 28 shows means for carrying this out by rotating the compressionpiston 3b within the compression ring 3a. This piston and ring arecomponents of a so-called compression head 50 which is movable upwardlyfrom the lowered position in which it is shown in FIG. 28 for engagementof the compression ring 3a with the transfer rings 1 and then forfurther upward movement for compression of the next to form thediaphragm. The compression head 50 comprises a block 51 having acylindric recess 52 at the top with an inwardly directed annular flange53 at the top of the recess providing an annular groove 54 below theflange. At 55 is indicated a compression piston support having acircular base 56 rotatable on a disk 57 of antifriction material(constituting a thrust bearing) seated in a circular recess 58 in thebase of recess 52. The compression piston support 55 has a stem 59extending upwardly from its base 56, the compression piston 3b beingsuitably secured coaxially on the upper end of the stem 59. At 60 isindicated a support for the compression ring 3a, this support comprisinga cylindrical body having a sliding fit in the annular flange 53, anoutwardly extending annular flange 61 at its lower end under the flange53 and an inwardly extending flange 62 at its upper end, stem 59 havinga sliding fit in the flange 62. The support 60 is adapted for limitedvertical sliding movement relative to the block 51 and the support 55,and carries the compression ring 3a on its upper end with thecompression ring held centered by the compression piston 3b. Thearrangement is such that on upward movement of the compression head 50,the compression ring 3a engages the lower transfer ring 1 and thenpushes both transfer rings 1 upward to clamp them against the injectionplate as appears in FIG. 1. At this point, the upper face of thecompression piston 3b is down below the top of the compression ring asshown in FIG. 1 for injection of the melt. After injection of the melt(as in FIG. 4), the compression head 50 is moved farther upward to movethe compression piston support 55 and the compression piston 3b upwardlyfor compression of the melt to form the diaphragm (as shown in FIG. 5).The stem 59 slides up within the flange 62 and the compression piston 3bslides up within the compression or clamp ring 3a. The compression ringsupport 60 is formed with a lateral slot 63 extending radially inwardfrom its outer periphery over the base 56 of the compression pistonsupport 55, and a lever 64 having its inner end secured at 65 to base 56extends radially outwardly through this slot. This lever is manipulableto effect the rotation of the compression piston support 55 and thecompression piston 3b for the circumferential orientation of theplastic. The slot may allow, for example, about a 30° swing of the lever64 and rotation of the piston 3b.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. Apparatus for making plastic containerscomprising means for first molding a pre-form and means for then moldingthe pre-form into a container having an open end, said pre-form moldingmeans comprising a transfer means having opposite sides, an aperturetherethrough from one side to the other, and a groove formationsurrounding the aperture adapted to receive plastic during the moldingof the pre-form and defining the configuration for the open end of thecontainer whereby said open end of the container is molded as anintegral part of the pre-form when the pre-form is molded, saidapparatus having a station for the molding of the pre-form, means atsaid station for closing the aperture in said transfer means comprisinga metering plate on one side and a compression means on the other sideof said transfer means at said station, said compression meanscomprising a compression ring and a compression piston movable in thecompression ring, said compression ring having an end engageable withthe said other side of the transfer means around said aperture atsubstantially the location of the groove formation in the transfermeans, said compression ring being movable relative to the meteringplate from an open position relative to the transfer means and themetering plate and a closed position wherein said end of the compressionring engages said other side of the transfer means and clamps thetransfer means between the metering plate and the compression ringthereby to form a closed space including the aperture in the transfermeans and said groove formation for the molding of the pre-form, saidmetering plate having a passage for flow of plastic into said closedspace, means for delivering into said closed space through said passagein the metering plate a volume of thermoplastic plastic less than thevolume of said closed space, said compression piston then being movablein and relative to said compression ring in the direction toward themetering plate to compress the plastic in said closed space and form itinto the pre-form with the plastic filling said groove formation therebyto mold the open end of the container which is to be formed from saidpre-form as an integral part of the pre-form and also to retain thepre-form in the transfer means.
 2. Apparatus as set forth in claim 1wherein said passage comprises a hole in the metering plate, and saiddelivery means comprises a nozzle movable laterally between a deliveryposition for delivery of the plastic through said hole and a shut-offposition wherein the nozzle is closed by the metering plate and closessaid hole to close said space for the compression of the plastic by saidcompression piston, said hole opening directly into the said space andformed so that plastic compressed in said hole constitutes part of thepre-form and is separable with the pre-form from the metering plate. 3.Apparatus as set forth in claim 1, wherein the groove formation of thetransfer means is configured to form an outwardly projecting rim for thecontainer, and wherein the transfer means carrying the pre-form ismovable to a molding station at which it is positionable on a moldhaving a cavity corresponding to the shape of the container for formingthe pre-form into a container in the mold cavity, the transfer meanscomprising an upper part and a lower part which are separable axiallywith respect to the container for separation of said rim from saidparts, the upper part being formed to form the top of the rim and thelower part being formed to form the bottom of the rim, said parts beingaxially separable by relatively moving said upper part away from the topof the rim and the lower part away from the bottom of the rim and to aposition wherein said parts are spaced a distance greater than theheight of the container and the said lower part is sufficiently clear ofthe bottom of the container to enable the container to be removedlaterally between said parts.
 4. Apparatus as set forth in claim 3wherein the transfer means comprises an upper ring and a lower ringwhich are axially separable, said apparatus having pin means for movingthe upper ring axially relative to the container to a position above therim and the lower ring axially relative to the container to a positionbelow the bottom of the container.
 5. Apparatus as set forth in claim 4,wherein the lower ring has a downwardly flaring seat and the upper ringhas an upwardly flaring seat around said aperture, the compression ringhaving a flaring upper end engageable with the seat of the lower ringand the metering plate having a lower portion formed to fit in theaperture in the upper ring and having a flaring periphery engageable bythe seat of the upper ring.
 6. Apparatus as set forth in claim 1,wherein the transfer means comprises a single transfer ring having saidgroove formation on the said other side thereof.
 7. Apparatus as setforth in claim 6, wherein the groove formation comprises a reversetapered groove.
 8. Apparatus as set forth in claim 1, wherein thetransfer means comprises a single transfer ring having said grooveformation on the said one side thereof.